Iron-based composite catalyst for phenol alkylation reaction, preparation method and application thereof

Abstract

The application relates to the technical field of petroleum chemical industry, in particular to an iron-based composite catalyst for phenol alkylation reaction and a preparation method and application thereof. The iron-based composite catalyst comprises an active component and a carrier component. The active component comprises oxides of iron, indium and copper, and the molar ratio of the three elements iron, indium and copper is 100:(5-20):(10-30), and the carrier is silicon dioxide. The catalyst forms a synergistic active center through the oxide combination state of iron, copper and indium, and in the gas phase catalytic reaction of methanol and phenol, the phenol exhibits high conversion rate and excellent ortho selectivity, the average conversion rate of phenol reaches more than 70%, the total selectivity of ortho products reaches 99%, the catalyst is suitable for the industrialized continuous production demand, and has a good application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of petroleum chemical industry, in particular to an iron-based composite catalyst for phenol alkylation reaction and a preparation method and application thereof. BACKGROUND

[0002] The ortho-position products of phenol alkylation with methanol are o-cresol and 2,6-dimethylphenol, both of which are very important fine chemical intermediates. o-Cresol is an intermediate for synthesizing pesticides, medicines, resins, spices, antioxidants and other products. o-Cresol can be applied in the synthesis of o-cresol formaldehyde resin, o-cresol formaldehyde epoxy resin, phenoxy carboxylic acid herbicide, and can also be used for producing o-hydroxybenzaldehyde, dyes, spices and antioxidants. 2,6-Dimethylphenol is a monomer for preparing polyphenyl ether (PPO), one of the five engineering plastics, and an engineering plastic modifier, and is also a synthetic raw material for some important pharmaceutical intermediates, which has important applications in pharmaceuticals, medicines, military industry and aviation.

[0003] At present, the main method for synthesizing o-cresol is the reaction of phenol with methanol. After phenol and methanol are vaporized, alkylation reaction occurs under the action of a catalyst, mainly oxygen alkylation to generate anisole, carbon alkylation to generate o-cresol and 2,6-dimethylphenol, and a small amount of 2,4,6-trimethylphenol is also produced as a byproduct. In the field, magnesium oxide was initially used as a catalyst to achieve industrialization, and then iron-based catalysts, manganese-based catalysts and vanadium-based catalysts were developed. Among them, manganese-based and magnesium-based catalysts require a relatively high reaction temperature of 400°C to 500°C, and the catalysts have a short service life; iron-based catalysts have the advantages of high activity and low reaction temperature.

[0004] Patent application CN101514144A uses Fe-Mg-Ce catalyst, the evaluation conditions are phenol:dimethylphenol:methanol:water=34:10:38:18 (mass ratio), the space velocity is 1.2h -1 , and under normal pressure, N2 is used as the carrier gas, the catalyst service life can reach 500 hours at a reaction temperature of 280°C to 450°C, the average conversion rate of phenol is 33.4%, and the selectivity of o-cresol is 96%. Although the selectivity of o-cresol is high, the conversion rate of phenol is not high, the catalyst activity is low, and additional dimethylphenol needs to be added in the reactants, and the yield of 2,6-dimethylphenol is very low.

[0005] Patent application 202411319917.8 uses metal crystal tip stone ZnAl2O4 catalyst, the evaluation conditions are phenol:methanol=2.3:1, the space velocity is 1h -1The life of the catalyst can reach 720h, the average conversion rate of phenol is 40%, and the total ortho-position selectivity is 90% when the reaction temperature is 250-280℃ under the pressure of 0.1MPa and with N2 as the carrier gas. Although the reaction temperature is low, the conversion rate of phenol and the ortho-position selectivity are not high.

[0006] It is found from the above research data that, in the gas-phase alkylation reaction of phenol and methanol, the total ortho-position selectivity is low when the conversion rate is high, the total ortho-position selectivity is high when the conversion rate of phenol is low, and the yield of 2,6-dimethylphenol is low. The existing technology has problems such as low overall yield of o-cresol, uncontrolled ratio of o-cresol and 2,6-dimethylphenol, and short life. SUMMARY

[0007] Therefore, it is necessary to provide a catalyst with high activity at low temperature, strong stability and long service life. When the catalyst is used to catalyze the alkylation reaction of phenol, the average conversion rate of phenol is more than 95%, the total selectivity of ortho-position products is more than 99%, the total ortho-position selectivity is high, the product ratio is controllable, the by-products are few, the production cost is reduced, and the atomic utilization rate is high. Further, a preparation method and application of an iron-based composite catalyst for the alkylation reaction of phenol are provided.

[0008] To achieve the above-mentioned purpose, the present application first provides an iron-based composite catalyst for the alkylation reaction of phenol, which comprises an active component and a carrier component; the active component is a composite metal oxide formed by oxides of iron, indium and copper, and the molar ratio of the three elements iron, indium and copper is 100:(5-20):(10-30), and the carrier is silicon dioxide.

[0009] The soluble silicate, iron salt, indium salt, copper salt and precipitant are subjected to a co-precipitation reaction at 40-55℃, and the pH at the end of the reaction is controlled to be 8-9. The obtained precipitate is aged at 40-55℃ for 3-5h, and then filtered, washed and dried to obtain a catalyst precursor. Subsequently, the catalyst precursor is calcined at 250-350℃ for 3-5h and at 450-600℃ for 5-8h to obtain the iron-based composite catalyst.

[0010] For example, the molar ratio of the three elements iron, indium and copper in the iron-based composite catalyst can be 100:5:10, 100:6:12, 100:7:15, 100:12:25, 100:15:30, 100:8:12, 100:17:30, 100:20:30 or 100:5:25, or any ratio within the above range.

[0011] Preferably, the molar ratio of the three elements iron, indium and copper is 100:(7-17):(12-30).

[0012] Preferably, the active component comprises a complex metal oxide formed from oxides of iron, indium and copper.

[0013] Based on one general inventive concept, the application further provides a preparation method of the iron-based composite catalyst, comprising the following steps:

[0014] S1, dissolving a soluble silicate in water to configure a silicon-containing solution;

[0015] S2, dissolving a soluble iron salt, a soluble indium salt and a soluble copper salt in water, adding a dispersant to configure a mixed salt solution;

[0016] S3, mixing the mixed salt solution with the silicon-containing solution, stirring at 40-55°C, and slowly adding a precipitant for co-precipitation reaction, with the reaction end point pH value controlled at 8-9;

[0017] S4, after the completion of the precipitation reaction, aging at 40-55°C for 3-5h; then sequentially performing filtration, washing, drying and crushing to obtain a catalyst precursor powder;

[0018] S5, calcining the catalyst precursor powder at 250-350°C for 3-5h, and then raising the temperature to 450-600°C for calcination for 5-8h.

[0019] Preferably, the soluble iron salt is selected from one of ferric nitrate hydrate, ferric sulfate hydrate and ferric chloride hydrate.

[0020] Preferably, the soluble indium salt is selected from one of indium nitrate hydrate, indium sulfate hydrate and indium acetate hydrate.

[0021] Preferably, the soluble copper salt is selected from one of copper nitrate hydrate, copper sulfate hydrate and copper chloride hydrate.

[0022] Preferably, the soluble silicate is selected from sodium metasilicate hydrate.

[0023] Preferably, the dispersant is selected from acrylic copolymer or polyvinyl alcohol copolymer.

[0024] Preferably, the precipitant is ammonia water. Further preferably, the precipitant is ammonia water solution with a mass concentration of 25%.

[0025] Preferably, in step S4, the end point of the washing is that the conductivity of the last time of the filtrate of the washing filter cake is reduced to 100-500μS / cm.

[0026] Preferably, in step S4, the drying temperature is 100-150°C.

[0027] Based on the overall inventive concept, the application further provides an application of the above-mentioned iron-based composite catalyst in the preparation of o-cresol and 2,6-dimethylphenol through catalyzing phenol alkylation reaction.

[0028] Preferably, the reaction raw material of the phenol alkylation reaction comprises phenol, methanol and water.

[0029] Preferably, the molar ratio of phenol, methanol and water is 1: (3-5): (0.5-1).

[0030] Preferably, the conditions of the alkylation reaction comprise: the reaction temperature is 300-350℃, the reaction pressure is 0.1-1.0 MPa, the raw material mass space velocity is 1.1-2.0 h -1 ~2.0 h -1 .

[0031] Further preferably, the alkylation reaction temperature is 340-350℃.

[0032] The catalytic mechanism of the iron-based catalyst of the application:

[0033] The catalyst provided by the application forms a synergistic active center through the oxide combination state of iron, copper and indium. Among them, iron (Fe) constitutes the main active phase (magnetite Fe3O4), which is the base of the catalytic reaction. Copper (Cu) promotes the conversion of trivalent iron to tetravalent iron, changes the electron cloud density of the iron active site, thereby enhancing the surface acidity; it can also promote the migration of hydroxyl groups, making it easier for methanol to dehydrate to form methyl carbonium ion CH3 + . The introduction of indium (In) can reduce the attack of methyl carbonium ion CH3 + on the electron-rich oxygen atom of the phenol hydroxyl group, reduce the generation of anisole, and improve the ortho selectivity. Further, by adjusting the ratio of indium, copper and iron, the redox performance and surface acidity of the catalyst can be optimized, thereby realizing precise control of the selectivity of o-methylphenol and 2,6-dimethylphenol.

[0034] Compared with the prior art, the application has the following beneficial effects:

[0035] (1) The iron-based composite catalyst provided by the application exhibits high conversion rate and excellent ortho selectivity in the gas phase catalytic reaction of methanol and phenol, the average conversion rate of phenol reaches more than 70%, and the total selectivity of ortho products reaches 99%, which is suitable for industrial continuous production needs and has good application prospect.

[0036] (2) The total selectivity of the ortho-position product reached 99%, which is a revolutionary advantage; this is much higher than traditional catalysts, meaning that the raw material utilization rate is very high, and the subsequent separation and purification cost is greatly reduced. By introducing indium elements, the generation of by-products such as anisole is fundamentally inhibited, and the product purity is improved.

[0037] (3) The iron-based composite catalyst provided by the present application can realize precise regulation of the phenol alkylation reaction product. The adjustable characteristics of the proportion of the elements can adapt to different product demands (such as focusing on the production of o-methylphenol or 2,6-dimethylphenol), and the application flexibility is high. DETAILED DESCRIPTION

[0038] The embodiments described in the specification are merely for the purpose of explaining the present application and are not intended to limit the present application.

[0039] For simplicity, only some numerical ranges are explicitly disclosed herein. However, any lower limit can be combined with any upper limit to form a range not explicitly recited; and any lower limit can be combined with other lower limits to form a range not explicitly recited, as can any upper limit with any other upper limit to form a range not explicitly recited. Furthermore, although a range of endpoints is recited, each point or individual number within the range is also included in the range. Thus, each point or individual number can be combined with any other point or individual number to form a range not explicitly recited.

[0040] The present application is further illustrated by the following examples. It should be understood that these examples are merely for illustrative purposes, since various modifications and variations will be apparent to those skilled in the art in light of the disclosure. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are on a mass basis, and all reagents used in the examples are commercially available or synthesized according to conventional methods and used as received without further purification, and the instruments used in the examples are commercially available.

[0041] The template agent used in the present application is a conventional template agent including but not limited to polyethylene glycol, polyvinyl alcohol, and the like.

[0042] Preparation Example 1: Preparation of Fe / In / Cu@SiO2 catalyst.

[0043] S1, 106.07 g of sodium metasilicate pentahydrate was dissolved in 500 g of deionized water at 50°C to prepare solution A.

[0044] S2, 202 g of iron nitrate nonahydrate, 15.04 g of indium nitrate hydrate, 30.2 g of copper nitrate hexahydrate were dissolved in 500 g of deionized water, 2.47 g of a template agent was added, stirred uniformly, and solution B was prepared.

[0045] S3, solution A and solution B were mixed uniformly to prepare solution C, and 25% ammonia solution was added dropwise to the above system while stirring, and the dropping was stopped when pH = 8, and the stirring was continued for 3 h after the addition of ammonia was completed.

[0046] S4, the precipitate obtained after aging was filtered and washed, and the conductivity of the last filtrate of the washed filter cake was 500 μs / cm 3 The washed solid was dried at 100°C for 15 h, and ground into powder.

[0047] S5, the powder was calcined at 300°C for 3 h, and then calcined at 400°C for 6 h, and catalyst 1 was prepared after shaping.

[0048] Preparation of Fe / In / Cu@SiO2 catalyst.

[0049] S1, 142.1 g of sodium metasilicate nonahydrate was dissolved in 500 g of deionized water at 50°C under stirring to prepare solution 1.

[0050] S2, 202 g of iron nitrate nonahydrate, 25.88 g of indium sulfate hydrate, 18.12 g of copper nitrate hexahydrate were dissolved in 500 g of deionized water, 4.92 g of a template agent was added, stirred uniformly, and solution 2 was prepared.

[0051] S3, solution 1 and solution 2 were mixed uniformly to prepare solution 3, and 25% ammonia solution was added dropwise to the above system while stirring, and the dropping was stopped when pH = 9, and the stirring was continued for 4 h after the addition of ammonia was completed.

[0052] S4, the precipitate obtained after aging was filtered and washed, and the conductivity of the last filtrate of the washed filter cake was 400 μs / cm 3 The washed solid was dried at 120°C for 12 h, and ground into powder.

[0053] S5, the powder was calcined at 350°C for 2 h, and then calcined at 450°C for 5 h, and catalyst 2 was prepared after shaping.

[0054] Preparation of Fe / In / Cu@SiO2 catalyst.

[0055] S1, 106.07 g of sodium metasilicate pentahydrate was dissolved in 500 g of deionized water at 50°C under stirring to prepare solution A.

[0056] S2, 139 g of ferrous sulfate heptahydrate, 30.0 g of indium acetate hydrate, 24.97 g of copper sulfate pentahydrate were dissolved in 500 g of deionized water, 3.88 g of a template agent was added, stirred uniformly, and configured into solution B.

[0057] S3, after solution 1 and solution 2 were mixed uniformly to configure solution 3, 25% concentration of ammonia solution was added dropwise to the above system while stirring, and the dropping was stopped when pH = 8.5, and after the ammonia water was added dropwise, the stirring was continued to age for 5 h.

[0058] S4, the precipitate obtained after aging was filtered and washed, and the washing was continued until the conductivity was 400 μs / cm 3 The washed solid was dried at 110°C for 13 h, and ground into powder.

[0059] S5, the powder was calcined at 250°C for 4 h, and then calcined at 500°C for 7 h, and catalyst 3 was prepared after shaping.

[0060] Preparation of Fe / In / Cu@SiO2 catalyst.

[0061] S1, 106.07 g of sodium metasilicate pentahydrate was dissolved in 500 g of deionized water at 50°C under stirring, and configured into solution 1.

[0062] S2, 135.15 g of ferric chloride hexahydrate, 6.47 g of indium sulfate hydrate, and 25.575 g of copper chloride dihydrate were dissolved in 500 g of deionized water, 3.34 g of a template agent was added, stirred uniformly, and configured into solution 2.

[0063] S3, after solution 1 and solution 2 were mixed uniformly to configure solution 3, 25% concentration of ammonia solution was added dropwise to the above system while stirring, and the dropping was stopped when pH = 8.3, and after the ammonia water was added dropwise, the stirring was continued to age for 6 h.

[0064] S4, the precipitate obtained after aging was filtered and washed, and the washing was continued until the conductivity was 400 μs / cm 3 The washed solid was dried at 150°C for 10 h, and ground into powder.

[0065] S5, the powder was calcined at 300°C for 4 h, and then calcined at 600°C for 5 h, and catalyst 4 was prepared after shaping.

[0066] Preparation of Fe / In / Cu@SiO2 catalyst.

[0067] S1, 142.1 g of sodium metasilicate nonahydrate was dissolved in 500 g of deionized water at 50°C under stirring, and configured into solution 1.

[0068] S2, 202 g of iron nitrate nonahydrate, 25.57 g of indium nitrate hydrate, 21.74 g of copper nitrate hexahydrate were dissolved in 500 g of deionized water, 4.98 g of a template agent was added, stirred uniformly, and configured into solution 2.

[0069] S3, after solution 1 and solution 2 were mixed uniformly to configure solution 3, 25% concentration of ammonia water solution was added dropwise to the above-mentioned system while stirring, and the dropping was stopped when pH = 8.8, and after the ammonia water was added dropwise, the stirring was continued to age for 8 h.

[0070] S4, the precipitate obtained after aging was filtered and washed, and the washing was continued until the conductivity was 500 μs / cm 3 The washed solid was dried at 120°C for 13 h, and ground into powder.

[0071] S5, the powder was calcined at 320°C for 5 h, and then calcined at 550°C for 8 h, and catalyst 5 was prepared after shaping.

[0072] Comparative Preparation Example 1 prepared Fe catalyst.

[0073] S1, 202 g of iron nitrate nonahydrate was dissolved in 500 g of deionized water, 2.02 g of a template agent was added, stirred uniformly, and configured into solution.

[0074] S2, 25% concentration of ammonia water solution was added dropwise to the above-mentioned system while stirring, and the dropping was stopped when pH = 8, and after the ammonia water was added dropwise, the stirring was continued to age for 3 h.

[0075] S3, the precipitate obtained after aging was filtered and washed, and the washing was continued until the conductivity was 500 μs / cm 3 The washed solid was dried at 100°C for 15 h, and ground into powder.

[0076] S4, the powder was calcined at 300°C for 3 h, and then calcined at 400°C for 6 h, and catalyst was prepared after shaping.

[0077] Comparative Preparation Example 2 prepared Fe / In / Cu catalyst.

[0078] S1, 202 g of iron nitrate nonahydrate, 30.08 g of indium nitrate hydrate, 18.12 g of copper nitrate hexahydrate were dissolved in 500 g of deionized water, 5.0 g of a template agent was added, stirred uniformly, and configured into solution.

[0079] S2, 25% concentration of ammonia water solution was added dropwise to the above-mentioned system while stirring, and the dropping was stopped when pH = 8, and after the ammonia water was added dropwise, the stirring was continued to age for 3 h.

[0080] S3, the precipitate obtained after aging was filtered and washed, and the washing was continued until the conductivity was 500 μs / cm 3The washed solid was dried at 100°C for 15h and ground into powder.

[0081] S4, the powder was calcined at 300°C for 3h and then at 400°C for 6h, and the catalyst was prepared after molding.

[0082] Comparative Preparation Example 3 was used to prepare Fe / Cu@SiO2catalyst.

[0083] S1, 106.07g of sodium metasilicate pentahydrate was dissolved in 500g of deionized water at 50°C to prepare solution 1.

[0084] S2, 130.15g of ferric chloride hexahydrate and 59.675g of copper chloride dihydrate were dissolved in 500g of deionized water, 3.80g of a template agent was added and stirred to prepare solution 2.

[0085] S3, solution 1 and solution 2 were mixed to prepare solution 3, and 25% ammonia solution was added dropwise to the above system while stirring, and the dropping was stopped when the pH was 8, and the stirring was continued for 3h after the addition of ammonia was completed.

[0086] S4, the obtained precipitate after aging was filtered and washed until the conductivity was 500μs / cm3, and the washed solid was dried at 100°C for 15h and ground into powder.

[0087] S5, the powder was calcined at 300°C for 3h and then at 400°C for 6h, and the catalyst was prepared after molding.

[0088] Comparative Preparation Example 4 was used to prepare Fe / In / @SiO2catalyst.

[0089] S1, 106.07g of sodium metasilicate pentahydrate was dissolved in 500g of deionized water at 50°C to prepare solution 1.

[0090] S2, 202g of ferric nitrate nonahydrate and 105.28g of indium nitrate hydrate were dissolved in 500g of deionized water, 3.07g of a template agent was added and stirred to prepare solution 2.

[0091] S3, solution 1 and solution 2 were mixed to prepare solution 3, and 25% ammonia solution was added dropwise to the above system while stirring, and the dropping was stopped when the pH was 8, and the stirring was continued for 3h after the addition of ammonia was completed.

[0092] S4, the obtained precipitate after aging was filtered and washed until the conductivity was 500μs / cm 3 , the washed solid was dried at 100°C for 15h and ground into powder.

[0093] S5, the powder is calcined at 300℃ for 3h, then calcined at 400℃ for 6h, and the catalyst is prepared after molding.

[0094] Comparative Preparation Example 5: Fe / La / Cu@SiO2 catalyst is prepared.

[0095] S1, 106.07g of sodium metasilicate pentahydrate is dissolved in 500g of deionized water at 50℃ to prepare solution 1.

[0096] S2, 202g of iron nitrate nonahydrate, 43.3g of lanthanum nitrate hexahydrate, and 18.12g of copper nitrate hexahydrate are dissolved in 500g of deionized water, 5.27g of a template agent is added and stirred uniformly to prepare solution 2.

[0097] S3, after mixing solution 1 and solution 2 uniformly to prepare solution 3, 25% ammonia solution is added dropwise to the above system while stirring, and the dropping is stopped when pH=8, and the stirring is continued for 3h after the ammonia solution is added dropwise.

[0098] S4, the obtained precipitate after aging is filtered and washed until the conductivity is 500μs / cm 3 , the washed solid is dried at 100℃ for 15h, and is ground into powder;

[0099] S5, the powder is calcined at 300℃ for 3h, then calcined at 400℃ for 6h, and the catalyst is prepared after molding.

[0100] Comparative Preparation Example 6: Fe / In / Cu@SiO2 catalyst is prepared.

[0101] S1, 106.07g of sodium metasilicate pentahydrate is dissolved in 500g of deionized water at 50℃ to prepare solution 1.

[0102] S2, 125.1g of ferrous sulfate, 2.588g of indium sulfate hydrate, and 41.2g of copper sulfate pentahydrate are dissolved in 500g of deionized water, 3.38g of a template agent is added and stirred uniformly to prepare solution 2.

[0103] S3, after mixing solution 1 and solution 2 uniformly to prepare solution 3, 25% ammonia solution is added dropwise to the above system while stirring, and the dropping is stopped when pH=8, and the stirring is continued for 6h after the ammonia solution is added dropwise.

[0104] S4, the obtained precipitate after aging is filtered and washed until the conductivity is 400μs / cm3, the washed solid is dried at 100℃ for 15h, and is ground into powder.

[0105] S5, the powder is calcined at 300℃ for 3h, then calcined at 400℃ for 6h, and the catalyst is prepared after molding.

[0106] The parameters for preparing the iron-based catalysts in each preparation example and the comparative preparation example are shown in Table 1.

[0107]

[0108] The following is the application of the iron-based composite catalysts obtained in each preparation example and the comparative preparation example in the preparation of o-phenol and 2,6-dimethylphenol in the phenol alkylation reaction.

[0109] Example 1

[0110] A fixed bed reactor tube with an inner diameter of 15 mm was filled with 20 g of the catalyst prepared in each of Preparation Examples 1 to 5, respectively, so that the catalyst bed was in the constant temperature section of the fixed bed reactor heating furnace, the reactor temperature was raised to 350℃, a homogeneous reaction liquid was prepared by mixing phenol, methanol and water in a molar ratio of 1:3:0.5, and was input into the reaction system through a metering pump, the reaction pressure was controlled at 0.15 MPa, and the reaction space velocity was 1 h -1 After the reaction for 200 h, the reaction liquid was sampled and analyzed by gas chromatography to analyze the mass content of each component in the reaction liquid.

[0111] Example 2

[0112] The preparation method of this example 2 is basically the same as that of example 1, the main difference is that the phenol alkylation reaction conditions are different, the phenol alkylation reaction conditions of this example are that the molar ratio of the reaction raw materials phenol, methanol and water is 1:4:0.5, the temperature is 340℃, the reaction pressure is 0.3 MPa, and the mass space velocity is 1.5 h -1 .

[0113] Example 3

[0114] The preparation method of this example 3 is basically the same as that of example 1, the main difference is that the phenol alkylation reaction conditions are different, the phenol alkylation reaction conditions of this example are that the molar ratio of the reaction raw materials phenol, methanol and water is 1:5:1, the temperature is 340℃, the reaction pressure is 0.5 MPa, and the mass space velocity is 2 h -1 .

[0115] Comparative Example 1

[0116] The preparation method of this comparative example is basically the same as that of example 1, the main difference is that the type of catalyst used is different, the catalyst used in this comparative example is the catalyst prepared in comparative preparation examples 1 to 6.

[0117] Comparative Example 2

[0118] The preparation method of this comparative example is basically the same as that of example 2, the main difference is that the type of catalyst used is different, the catalyst used in this comparative example is the catalyst prepared in comparative preparation examples 1 to 6.

[0119] Comparative Example 3

[0120] The preparation method of the present comparative example is basically the same as that of Example 3, the main difference is that the type of catalyst used is different, the catalyst used in the present comparative example is prepared according to Comparative Preparation Examples 1-6.

[0121] The conversion rate of phenol and the selectivity of the corresponding components in each example and comparative example are calculated according to the following method:

[0122] The calculation formula of the conversion rate of phenol is: phenol conversion rate = molar amount of converted phenol / total molar amount of phenol before reaction x 100%;

[0123] The calculation formula of the selectivity of o-methylphenol is: o-methylphenol selectivity = molar amount of o-methylphenol generated in the reaction / molar amount of converted phenol x 100%;

[0124] The calculation formula of the selectivity of 2,6-dimethylphenol is: 2,6-dimethylphenol selectivity = molar amount of 2,6-dimethylphenol generated in the reaction / molar amount of converted phenol x 100%.

[0125] The results of the phenol alkylation reaction in each example and comparative example are shown in Table 2.

[0126]

[0127]

[0128] From the data in Table 2, it can be found that the iron-based composite catalyst prepared according to the technical solution of the present application in Examples 1-3 has an average phenol conversion rate of more than 70%, a total selectivity of ortho products of more than 99%, less by-products, and an impurity content as low as 0.33wt%, and can realize flexible adjustment of the production capacity of ortho-methylphenol and 2,6-dimethylphenol by adjusting the ratio of the active components of the catalyst and the ratio of the reaction raw materials. The catalyst can be stably operated for 200h per pass, and the overall performance is better than that of the same type of catalyst prepared by the prior art.

[0129] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present application, and these modifications or replacements should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An iron-based composite catalyst for phenol alkylation reaction, characterized by, The iron-based composite catalyst comprises an active component and a carrier component; the active component comprises a composite metal oxide formed by oxides of iron, indium and copper, and the molar ratio of the three elements of iron, indium and copper is 100: (5-20): (10-30), and the carrier is silicon dioxide; The preparation method of the iron-based composite catalyst comprises the following steps: The soluble silicate, iron salt, indium salt, copper salt and precipitant are subjected to co-precipitation reaction at 40-55 DEG C, and the end-point pH of the reaction is controlled to be 8-9; the obtained precipitate is aged for 3-5 hours at 40-55 DEG C, and then subjected to filtration, washing and drying to obtain a catalyst precursor; and then the catalyst precursor is calcined at 250-350 DEG C for 3-5 hours and then calcined at 450-600 DEG C for 5-8 hours to obtain the iron-based composite catalyst.

2. The method of claim 1, wherein the iron-based composite catalyst is prepared by the steps of: The preparation method comprises the following steps: S1, dissolving a soluble silicate in water to prepare a silicon-containing solution; S2, dissolving soluble iron salt, soluble indium salt and soluble copper salt in water, adding a dispersing agent to prepare a mixed salt solution; S3, mixing the mixed salt solution and the silicon-containing solution, stirring at 40-55 DEG C, and slowly adding a precipitant to perform co-precipitation reaction, and the end-point pH of the reaction is controlled to be 8-9; S4, after the completion of the precipitation reaction, aging for 3-5 hours at 40-55 DEG C; and then performing filtration, washing, drying and crushing to obtain a catalyst precursor powder; S5, calcining the catalyst precursor powder at 250-350 DEG C for 3-5 hours, and then increasing the temperature to 450-600 DEG C for calcination for 5-8 hours.

3. The method of claim 2, wherein, The preparation method satisfies at least one of the following conditions: (1) the soluble iron salt is selected from one of iron nitrate hydrate, iron sulfate hydrate and iron chloride hydrate; (2) the soluble indium salt is selected from one of indium nitrate hydrate, indium sulfate hydrate and indium acetate hydrate; (3) the soluble copper salt is selected from one of copper nitrate hydrate, copper sulfate hydrate and copper chloride hydrate; (4) the soluble silicate is selected from sodium metasilicate hydrate; (5) the dispersing agent is selected from acrylic copolymer or polyvinyl alcohol copolymer.

4. The preparation method according to claim 2, characterized in that, The precipitant is ammonia water.

5. The preparation method according to claim 2, characterized in that, In step S4, the end-point of the washing is that the conductivity of the filtrate is reduced to 100-500 muS / cm; and the drying temperature is 100-150 DEG C.

6. An application of the iron-based composite catalyst in claim 1 in catalyzing phenol alkylation reaction to prepare o-cresol and 2,6-dimethylphenol.

7. Use according to claim 6, characterized in that, The reaction raw materials of the phenol alkylation reaction comprise phenol, methanol and water.

8. Use according to claim 7, characterized in that, The molar ratio of the phenol, the methanol and water is 1: (3-5): (0.5-1).

9. Use according to claim 6, characterized in that, The conditions of the phenol alkylation reaction include: the reaction temperature is 300℃-350℃, the reaction pressure is 0.1 MPa-1.0 MPa, the mass space velocity of raw materials is 1.1 h -1 -2.0 h -1 .

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